When Pantheons Collide
by Author's Restraint
Summary: It was two weeks after the Titan War and the Greeks were celebrating on Olympus when three teenagers with mysterious marks on their skins fell from the ceiling. With them came a message from the Fates and two books from the future telling of the wars that were going to happen. Set two weeks after TLO and a month before CoFA.


**Sooo... welcome to When Pantheons Collide. Yes, it is a reading the books. I got this idea, mostly because I'd never seen anyone do one as a crossover. There was one on Fanfiction but it got deleted. Anywho, on with the story.**

**Disclaimer- I don't own TMI or PJO/HoO. They belong to Rick Riordan and Cassandra Clare respectively.**

Mt. Olympus' throne room was packed with demigods, satyrs, the new Oracle, nymphs and of course the gods. It was two weeks after the Titan War and they were all celebrating the defeat of Kronos. Things were finally at peace for the demigods. Percy and Annabeth had gotten together _finall_y but were both still somewhat in the awkward stage of transition from best friends to boyfriend and girlfriend.

Everything was finally at peace in the Greek world. Percy had gone back to school and so had Annabeth.

Chiron was sitting talking to Poseidon and they were having quite an animated conversation. Annabeth was talking to her mother about her plans to renovate Olympus and Athena was listening intently, very proud at the young woman her daughter had become. The one thing that bothered her though was the fact that Annabeth had chosen to date Barnacle Beard's sea spawn. Out of everyone, she'd chosen Percy Jackson, the disrespectful Son of Poseidon who'd turned down her father's offer of immortality. She was hoping that he'd choose it so Annabeth and him would forget about each other but _noooo._

Speaking of Percy, he was at the buffet table stuffing himself with food along with his brother, Tyson, Grover and The Stolls. What could you tell them? They were growing boys and growing boys needed to eat!

Clarisse and Chris were off in a corner by themselves enjoying some time alone together but if you'd ask Clarisse, she'd deny it immediately. She wasn't some helpless girl who thought only of her boyfriend. She was a warrior, a daughter of Ares, and Chris knew that and respected her because of that. That also meant that she could kick his ass without a second thought if he did anything remotely close to piss her off. That should have sparked some fear in him but it did quite the opposite in fact. He liked the fact that Clarisse was her own person and that she spoke her mind.

Artemis was talking to her Huntresses, Malcolm and a few Athena kids were talking about battle strategy and they looked as if they would pull out blank sheets of paper and begin to draw battle plans. Why they did it, no one knew. After all the war was finished and everyone wanted to avoid the topic of war altogether but hey, what could any of them do?  
Hades was talking to Hestia at the hearth and the topic of conversation was Hades' own child Nico who'd opted to stay out of anyone's eyesight and into the safety of the shadows. Though if you looked closely you could see a small humanoid figure sitting there eating a piece of cake with a wisp of a smile on his face.

"Brother, you have to talk to him," the gentle goddess said softly to her older brother. Hades' dark eyes, that resembled bottomless pits, narrowed. "I don't _have_to do _anythin_g," the god of the underworld snapped. Hestia smiled sadly at her elder brother. Despite being older than she was, he still hadn't learnt the importance of familial interaction. She couldn't blame him though. Kronos wasn't exactly the ideal father (having your father swallow you as a child tended to really mess you up). Then he was given to rule over the dead which did nothing to lift his spirits. Persephone was the only woman who was able to tame him a little. Along with Maria di Angelo, Nico's beautiful, Italian, _dead_ mother. Hestia believed her brother lost all faith in the Olympians, mostly Zeus seeing as her death was his fault, after that. He'd truly believed that he couldn't trust any of them anymore. (Not like he did anyway but that was beside the point). It was a miracle in itself that he fought with them against the Titans.

"Hades, look at him. The boy has no direction. He thinks he doesn't belong at the Camp and is constantly moving from place to place. He doesn't even think he has a family. You are all that the boy has and you may end up losing him if you don't _do somethin_g!" Hades frowned, hating the fact that his sister was right. Still... "I miss Bianca," he admitted softly. Hestia sighed. "I know you do. But she's dead and there's nothing that's going to change that. You forget that you're not the only one who has lost her. You can be bitter for the rest of your immortal life or yo can do something to make sure that the same thing that happened to Bianca doesn't happen to Nico as well."  
Hades glared at his sister. "I hate it when you're right."

Suddenly, they heard screams from the ceiling of the throne room. Everyone froze then sprang into action. The gods drew their weapons and so did the demigods, their instincts kicking in and causing them to get into defensive stances. The nmyphs and satyrs, though not armed with weapons, stood firm and fully prepared to use their magic if it came to that.

Three teenagers were falling from the sky. There was a flash of black and gold and before either of them could blink, blonde teenager dressed in all black landed gracefully on his feet and had drawn a blade that gleamed like glass. A black haired girl landed just as gracefully next to him. A red haired girl, unfortunately, wasn't so lucky. The blonde lept up and caught her in the air and landed on his feet with the grace of an angel.

Aphrodite's daughters stared at the newcomers in awe of their beauty. Obviously they weren't as beautiful as the Big Three's children but they were still pretty damn close.

The blonde boy looked as if he'd been dipped in gold. His tousled gold locks from what she could see because of the hood on his head, looked more of a dark gold. His eyes, though, were what made Annabeth's heart stop. They were bright gold. This boy reminded her of Luke. Annabeth looked around at everyone else, realizing that they all had the same train of thought as she. Hermes' eyes looked glassy.

The boy, who looked about seventeen, was tall about 5"11, only two inches taller than Annabeth and an inch shorter than Percy. He was muscular, that much was obvious from the strain put on his black short sleeved T-shirt. He was so tanned that his skin looked somewhat gold. Unlike Percy, whose skin was more of a dark bronze. He had a sharp jaw and prominent cheekbones and his eyelashes cast faint shadows over his cheeks.

His body was littered with scars and black tattoo like marks. They looked ancient and seemed to speak a different language. The gods gasped when they recognized them.  
'What is a _Nephilim _doing here?' was the thought running through all their minds.

The boy wore a tight, short sleeved black T-shirt under a sleeveless black leather jacket with a hood that was zipped up halfway and black pants made of some leather-like material along with black combat boots. A belt with numerous weapons was strapped to his waist and metal cuffs adorned his wrists.  
He put down the girl and placed her behind him protectively. She too, had drawn a blade. Something slithered along the black haired girl's wrist until it elongated into a deadly glowing whip of what Annabeth realized was electrum.

The girl was tall. Taller than Annabeth, Percy and the blonde boy, but that could have just been the seven inch black boots that reached her calves. Her hair was a river of ebony that cascaded down her back that made Annabeth feel jealous. She'd always wanted dark hair.

The girl had dark eyes and wore dark mascara and eyeliner and her skin was pale. She wore a blood red dress that reached mid-thigh, black stockings and a black trenchcoat. She too had black tattoo like marks all over her skin.

The red haired girl, who looked about 14-15, **(A/N-I know Clary's sixteen but the demigods don't know that because Clary is so tiny and petite), **peered at them over the blonde's protective arm. She looked a looked a lot like Rachel with her red hair, green eyes, freckles and porcelain skin. Though this girl's hair was more tamed curls while Rachel's hair was frizzier and Rachel's skin had a more pinkish hue to it and Rachel's eyes were a far brighter green than this girl's.

The girl, too wore black clothing like her two companions. She wore a black leather jacket over a black tank top along with a silver chain looped through a ring that was around her neck, black pants of the same material as the boy and black boots. Black tattoo like marks were on her skin as well.

"Where are we? Who are you?" the boy asked sharply.

"Nephilim," Zeus began, brandishing his lightning bolt. The boy's eyes widened comically but he still remained defiant.  
The demigods were confused.

"What are you doing here?" Poseidon asked, brandishing his trident. As soon as the question was asked, a note floated down from the sky and rested on the blonde boy's head. He picked it up and read aloud.

_"Dear gods, demigods, satyrs, nymphs and Nephilim,_  
_We have sent you two books for you to read about your future in order for you to win your upcoming wars-"_

Percy and Annabeth, along with the demigods groaned in disappointment. They _jus_t finished a war! Of course they wouldn't able to have any peace.

_"And in order for you all to understand each other better, so you'll beable to work together in the future. No maiming, no killing, demigods don't hurt your parents, parents don't hurt your children, etc. Nephilim introduce yourselves using your full name. That means you Jace._  
_Goodbye and goodluck._  
_Sincerely,_  
_Clotho, Atropos and Lachesis_  
_(The Fates)."_  
Realizing that they weren't enemies, the demigods relaxed their stances and put away their weapons.

The now identified Jace, crumpled up the paper and growled. The red head placed a hand on his arm affectionately. Aphrodite smiled, realizing the two of them were a couple.

"What does that mean?" the black haired girl, asked. She had an accent. Not quite British, but not quite American either.

"Honestly Isabelle, think. Isn't it obvious? We're on some alternate dimension where the Greek Gods are real and where reading books is going to somehow help us win whatever war that's not going to happen."

The gods fumed in outrage.

"You're not," Annabeth said.

The blonde turned to her and his amber eyes narrowed. "What?"

"In an alternate universe. You're not. The gods are real and your war is going to happen." _Just like ours, _Percy thought but didn't say. "You're in New York, the Empire State Building to be exact," Percy continued.

"Then how-?" The girl, Isabelle, asked.  
"Why don't we all introduce ourselves and then we'll talk about that, hmm?" Athena stated.

Jace, still adamant that they were in an alternate universe, reluctantly stepped forward. "Jonathan Christopher Herondale, Shadowhunter and member of the _New York Institute._"

Isabelle walked forward after him, making boys sigh dreamily at her. "Isabelle Sophia Lightwood, Shadowhunter and member of the _New York Institute._"

The red head walked over to Jace and laced their fingers together. She was pitifully short, about 5"2, so Jace towered over her. "Clarissa Fairchild- M-Morgenstern," she made a face at the last name but continued, "Shadowhunter and member of the _New York Institute._" Clary looked around at Olympus in utter amazement. Until that moment,_The Institute_ was the most beautiful place she'd ever been to. Along with Idris but this...this took the cake a million times over. Her fingers itched for her art utensils.

"What the hell is a shadowhunter?" Thalia asked, confused.

"They're a race of half human, half angel-"

"Wait, angels are real?!" Percy cried incredulously. Athena gave Percy a look that could have melted ice for interrupting her. Annabeth facepalmed at her boyfriend. "Seaweed Brain!" she hissed. Percy blushed in embarassent.

Athena refrained from strangling the sea spawn and continued. "As I was saying, they are a race of half human, half angel and they fight demons and rogue Downworlders and occasionally rogue shadowhunters." The aforementioned three tensed at this, remembering the Mortal War. It was a disheartening truth that their race had turned on each other.

"How do you know that?" Jace asked.

Athena gave a knowing smirk. "I am Athena, goddess of war, battle strategy, weaving and wisdom. I know _everything._"

The shadowhunters now seemed to understand that they were in the presence of gods and they looked highly uncomfortable. The blonde shadowhunter kept his body protectively in front of the tiny red head. "We've introduced ourselves. Now you do the same'" Isabelle said.

Percy stepped forward and Clary's fingers itched for her art utensils once more upon seeing him. Jace may have looked like an angel but this boy looked like a god. His black hair was windswept just so that looked like a raven's wings and his green eyes were a beautiful mixture of blues, greens, silvers and golds that it resembled the ocean perfectly. His jaw was shaped in such a way that it looked like someone had personally sculpted it to perfection. His cheekbones were high and prominent and his eyelashes were impossibly long like Jace's. His skin was more of a dark bronze, as opposed to Jace who was all gold, making his green eyes stand out against his dark hair and his shoulders were broad and built. Along wth his chest from what she could see due to the strain on his sea green t-shirt (Not that she was looking, anyway. Pfft) that brought out his eyes. His stomach was rigid and chiseled (Damn, those abs) as if he were made of marble. His arms were defined and muscular. His body was scarred but even those were a twisted type of beautiful.

"Percy Jackson, Son of Poseidon, God of the Seas and King of Atlantis, Hero and Savior of Olympus." Isabelle smiled flirtatiously, awestruck by his beauty.

Jace rolled his eyes at his girls. His sister and his girlfriend looked rather taken by this boy but he was determined not to trust him or anyone there.

Annabeth stepped forward. "Annabeth Chase, Daughter of Athena, Architect of Olympus and Heroine of Olympus." She glared at Isabelle and her stormy grey eyes seemed unnerve her and the blonde demigod took some satisfaction in that. No one, _no one, _flirted with her boyfriend. She had to fight too long to get him and now that she had him, no one was taking him away from her. She had to fight Rachel and Calypso to have him and now some shadowhunter dare flirt with him? Hades no. She took Percy's hand and dragged him away from the dark haired girl's line of sight. Aphrodite giggled in amusement.

"Thalia, just Thalia. Daughter of Zeus, King of the Gods-" Zeus grinned and lightning struck the sky overhead. Hades and Poseidon rolled their eyes. "Lieutenant of the Hunters of Artemis." Isabelle didn't want to admit it but this girl intimidated her. Her eyes looked charged with electricity.

Nico stepped out of the shadows and his eyes softened just a tad at looking at her. Percy, upon seeing his 'younger' cousin, moved to stand next to him and Thalia. Clary smiled at seeing that. She was reminded of the Lightwood siblings. "Nico di Angelo, Son of Hades, Lord of the Dead and God of the Underworld-" Nico shared a fleeting look with his father and Hades was surprised at this. "The Ghost King," Nico smirked devilishly at that, "Hero of Olympus."

Jace's grip tightened on the hilt of his seraph blade. This boy made him uneasy. His black eyes reminded him of Valentine. Thinking of his dead father caused an involuntary shiver of pain through him. He banished all thoughts of Valentine.

"Grover Underwood, Lord of the Wild," The shadowhunters, accostomed to the more..._strange_ features of Downworlders offered no reaction to Grover's horns or furry legs.

"Clarisse La Rue, Daughter of Ares, Heroine of Olympus," she said, stroking Maimer 2.0.

"Chris Rodriguez, Son of Hermes, Hero of Olympus."

"Travis Stoll, Son of Hermes, Hero of Olympus."

"Connor Stoll, Son of Hermes, Hero of Olympus."

"Will Solace, Son of Hermes, Hero of Olympus."

"Drew Tanaka, Daughter of Aphrodite." She looed at Isabelle's outfit appreciatively and winked at Jace who waved at her. Clary glared at her.

"Lacy, Daughter of Aphrodite."

"Mitchell, Son of Aphrodite."

"Katie Gardener, Daughter of Demeter, Heroine of Olympus."

"Butch, Son of Iris." Remembering that Iris was the rainbow goddess, Jace smirked. _Magnus would love this kid,_ he thought.

"Miranda Gardener, Daughter of Demeter, Heroine of Olympus."

"Lou Ellen, Daughter of Hecate, Heroine of Olympus."

"Malcolm, Son of Athena, Hero of Olympus."

"Clovis, Son of Hypnos," he said then resumed sleeping.

"Rachel Dare, Oracle of Delphi." The shadowhnters gasped when they saw her. "Whoa. Clary, do you have some twin we don't know about?" Isabelle asked.

"Ugh, no. I don't need anymore siblings," Clary said, thinking of Sebastian.

"Pollux, Son of Dionysus."

"I can't believe we were brought here to read books. _Books_!" Jace said in outrage to Clary.

The gods waved their hands and couches appeared. Jace sat down and pulled Clary into his lap. Isabelle sat next to them. Percy sat down and Annabeth sat next to him with his arm around her. Isabelle grumbled in disappointment but then shrugged. The gods, who were already shrunken down in mortal size, sat in the couches as well. There was a flash of light and when it disappeared, the minor gods besides Hecate and Iris were gone along with the nymphs and satyrs besides Grover.

Athena picked up the two books that had appeared when the light dissipated. "City of Fallen Angels and the-" Athena gasped and then dropped both books. "Mother! Are you alright?" Malcolm asked, worried..

"I'm fine, Malcolm. I was just startled."

Poseidon picked up the books. "City of Fallen Angels and The Mark of Athena." EVeryone turned to Athena who had her eyes closed and who was sighing resignedly.

"Just go on with it," she said exasperatedly.

"I'll read," Poseidon said. For once, Athena didn't make a comment about Barnacle Beard being able to read. She was too caught up in her thoughts.

The King of Atlantis cleared his throat and began.

**Soooo...How was it? I'll try to update as soon as I finish chapter 1.**


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